Method for processing slag

ABSTRACT

Iron-containing slag in flowable state is poured into a casting bed to form a layer. Upright tubular conduits are embedded in the layer during pouring, each having an upper section and a lower section telescoped from below over the bottom portion of the upper section. The upper sections have upper open ends outside the layer and explosive capsules are inserted through these into the lower sections and detonated. This ruptures the lower sections and forms in the slag layer cavities surrounding the lower sections. Cooling water is then introduced into the upper sections to flow into the layer via the lower sections and the cavities.

United States Patent 1191 Forschepiepe [4 1 Jan. 9, 1973 54 METHOD FOR PROCESSING SLAG 1,699,575 1/1929 Spies ..65 20 [76] Inventor: Fritz Forschepiepe, Asselner Hell- 22 3;: 8 106, Dmmund'Asseln, 3,203,776 8/1965 Rodis et a1 ..65/20 many [22} Filed; June 10 1970 Primary Examiner--Frank W. Miga [21] A l N 44 987 Att0rney-Michael S. Striker [57] ABSTRACT Foreign Application Priority Data Iron-containing slag in flowable state is poured into a June 14 1969 Germany ..P 19 30 394.7 Casting bed to form a Upright tubular conduits Oct. 18 Y 1969 Germany ..P 19 52 593.0 are embedded in the layer during Pouring each having an upper section and a lower section telescoped from 52 US. Cl. 65/19 65/20 65/21 below the the '65l22 The upper sections have upper open ends outside the [51] Int C1 C03, 5/18 C03b 19/10 d 5/22 layer and explosive capsules are inserted through [58] Fie'ld i 'gg 65/22 20 21 19 these into the lower sections and detonated. This ruptures the lower sections and forms in the slag layer [56] References Cited cavities surrounding the lower sections. Cooling water is then introduced into the upper sections to flow into UNITED STATES PATENTS the layer via the lower sections and the cavities.

1,888,394 11/1932 Schol ..65/l4l 4 Claims, 5 Drawing Figures PATENTEDJAN 9197s 3. 709371 MWENTOR Fmrz mus PATENTED JAN 9 I973 SHEET 2 (IF 2 METHOD FOR PROCESSING SLAG BACKGROUND OF THE INVENTION The present invention relates to the processing of slag, and more particularly to the processing of ironcontaining slag.

Iron-containing slag is obtained as a by-product of certain steel-making processes, including the so'called LDAC and LD methods. Conventionally such slag is taken via trucks or other conveyances from the furnace to a casting bed into which it is poured. To distribute the slag in the bed in form of a single or multiple layer, it is poured from overhead movable cranes or the like.

Frequently such slag contains substantial quantities of iron in liquid and/or solidified form, in addition to flowable slag and slag fragments which are solidified. The area over which this mass can be poured is limited by the span of the tracks for the cranes with the result that back-up during the flowing of the mass in the casting bed causes the formation of thick layers of slag and iron as well as of iron fragments which are embedded in slag or adhere to it. These layers are difficult to break up by means of mechanical gripping devices, such as mechanical grabs, shovels and the like. It is therefore customary to thoroughly wet the still hot slag, causing fractures to develop in it due to resulting internal stresses, and thus making it easier for the mechanical devices to engage and remove portions of the slag.

Slag which is a by-product of the LDAC process is used for making fertilizer. Slag resulting from the various other methods, however, is in part returned to the furnace and in part employed in highway construction. The latter use is connected with difficulties, however, because such slag contains embedded quantities of calcium compounds and dolomite which are surrounded by a shell of matter all or some of which may be in form of iron oxides, silicates or the like which shell is so tight that it is not readily penetrated by water and steam. The slag therefore contains non-slaked calcium and sinter dolomite which later sometimes only after a period of a year or more causes a localized expanding or blowing action in the road material incorporating the slag, and thus can lead to substantial damage.

Because of these considerations thorough wetting of the slag is essential to reach these inclusions insofar as is at all possible. On the other hand, such wetting is rather dangerous because, if the water contacts iron inclusions which are not yet solidified, explosions are likely to occur. Evidently the possibility that such inclusions may be present is the greater, as the wetting already begins during the actual pouring of the slag bed or layer to assure that the water penetrates to the bottom of the layer. The danger is especially great -and has in actuality led to explosionswhen non-systematic careless pouring of hot slag over small areas causes the formation of hollows and slag shells in which water accumulates, and if subsequently liquid iron intrudes into these cavities.

However, until now no approach has been found to avoid these difficulties in the processing of iron-containing slag.

SUMMARY OF THE INVENTION It is, accordingly, an object of the invention to overcome the above-outlined difficulties of the prior art.

More particularly it is an object of the present invention to provide a novel method of processing slag which overcomes these difficulties.

A concomitant object of the invention is to provide a novel arrangement for the processing of slag without encountering the above-mentioned difficulties.

In pursuance of the above objects, and others which will become apparent hereafter, one aspect of the invention resides in a novel method which, briefly stated, comprises the provision of a casting bed for the flowable slag, and the casting of the slag into this bed so as to form at least one layer therein. A plurality of tubular conduits is embedded in this layer and communicates with the exterior of the layer.

Now, portions of at least some of the conduits within the layer are explosively ruptured, thereby forming in the layer cavities which surround these portions. Cooling water is then introduced into the conduits and flows from the ruptured portions into the cavities, and from there penetrates the layer thoroughly.

The admission of cooling water, it is emphasized, takes place only after the entire slag layer (or layers) is completely solidified. No earlier admission is necessary because the invention provides for the desired excellent wetting of the entire layer despite the fact that it takes place only after solidification. Of course, this avoids the possibility that dangerous non-solidified quantities of iron could still be present at that time. The bed is preferably inclined, i.e. has an inclined rather than a level bottom wall.

According to a further embodiment of the invention, the conduits may be arranged along that lateral wall of the casting bed at which the slag is poured into the latter, spaced at requisite intervals which can be readily determined empirically. The entry of cooling water into the slag is then concentrated in the region of this lateral wall where the layered slag has its greates thickness or depth. Usually or preferably the bottom wall of the bed will slope downwardly away from this lateral wall and the water will thus penetrate downwardly and laterally away from the lateral wall through quickly developing cooled zones. In other words, the water becomes distributed between the loosely overlying layers of slag and through existing and newly developing tension cracks.

The supply of cooling water can of course be regulated so that strong temperature fluctuations in the slag are attainable, a feature which is especially desirable because of its effect with respect to the penetration of the shells surrounding calcium and dolomite inclusions. The cooling water may for instance be supplied in pulses.

The invention achieves a rapid distribution of the cooling water throughout the slag. One advantage of this is to provide for safe, rapid, temporary cooling of the slag. The concomitant formation of tension cracks results in the exposure of new and larger cooling surfaces where the incoming cooling water can contact and cool the slag. A further advantage is the separation of iron inclusions from the slag. The reason is that if the water flow is temporarily throttled, the slag reheats because of its still existing interior heat. When the water flow is then resumed or increased, strong thermal stresses result which are particularly effective in forming weak zones in the thin slag layers or plates when foreign bodies e.g. iron are embedded.

Still another advantage is the effect on the embedded calcium compounds and dolomite quantities, because the strong temperature fluctuations cause their shells to crack. Even small cracks, however, permit water and steam to enter the shells and to contact the calcium and dolomite, converting them into a muddy calcium hydrate mass which cannot revert to burnt-calcium state because of the progressing cooling effect.

The end result of processing according to the invention is that the casting bed will end up being filled with a mass of relatively small slag fragments which, after termination of the cooling water supply and after a short settling and draining period, can be removed as a dry crystalline material. This material can be readily further treated, including by known magnetic means, and especially advantageous and economical if LDAC- residue slags are so processed which are to be subsequently ground to make fertilizer. However, the invention is equally advantageous in processing slag resulting from the LD steel-making process, which is to be further converted to street-building material, especially because such material has been found to have no negative reactions when contacted with water.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic cross-section through a casting bed incorporating one embodiment of the invention;

FIG. 2 is a diagrammatic cross-section, on an enlarged scale, through a conductor for use in accordance with the invention;

FIG. 3 is a vertical fragmentary section through a further embodiment of the invention;

FIG. 4 is a-top-plan view of FIG. 3; and

FIG. 4a is a view similar to FIG. 4 but of another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing firstly FIGS. 1 and 2, it will be seen that reference numeral 5 identifies a conventional and therefore well-known casting bed for slag in flowable state. Here, the bottom wall of the casting bed 5 slopes downwardly in one direction as is frequently but not necessarily the case in such beds.

According to the invention there is provided a plurality of tubular conduits composed of an upper (or first) section 1 and a discrete lower or sec section 2, with the sections being telescoped together. The upper sections 1 are provided with supporting arms 4 which are connected to them at 3 preferably articulately and which support the sections 1 and 2 in desired position while slag is poured into the bed 5. The free lower ends of arms 4 are provided with plates 6 which serve to facilitate support on the bottom wall and which may be releasably fastened in any desired manner to the bottom wall.

The lower ends of the tubular sections 2 are closed, but the upper free ends'of the sections 1 are open. They are provided with connectors by means of which the sections 1 can be connected with a supply network 8 for cooling water.

After casting of the slag is completed, an explosive device is introduced into each section 2 via the open end of its associated section 1, and is then detonated. These devices, in form of explosive caps or the like, are not novel and the only essential requirement is that their explosive action be such as to rupture the closed lower end of the respective section 2 and to simultaneously form a cavity in the surrounding slag, but without destroying large areas of the slag layer or layers.

Once this is accomplished, cooling water is admitted through the sections 1 into the sections 2 and from there into the surrounding cavities. From these cavities it seeks its way through the explosively caused cracks radiating from the cavities and of course any other existing cracks through the layer of slag, causing new cracks to form as a result of internal tensions due to contact of the water with the hot slag. The layer thus becomes evenly wetted throughout, with the results discussed earlier.

In the embodiment of FIGS. 3 and 4, the conduits composed of the sections 1 and 2 are arranged spaced along the upright lateral wall 9 of the casting bed 5, in the region of which the slag is poured into the bed. The sections 1 are connected to the water supply network 11 via the pipes 10 and a valve is provided which,

operable by the rod 12 located above the track for the slag distributing vessel or vehicle, makes it possible to regulate the admission ofcooling water.

In this embodiment the sections 2 are telescoped from below over the open lower ends of the sections 1, and in turn either have open or closed lower ends. In the region of their lower ends the sections 2 are provided in their wall with weakened-zones, such as longitudinally extending slots 13, the wall thickness and the slots being so selected that detonation of the explosive charge again introduced via the upper open ends of section 1 readily ruptures the lower ends of sections 2 and causes the formation of surrounding cavities. It is recalled here that the explosive charges are to be so weak as to just be able to achieve the in tended purposes.

Above the slag layers 14 which are poured below the sections 2, the sections 1,2 and pipes 10 are directly surrounded with cold fragments 15 of slag, rather than with poured slag. The purpose of this is to prevent during further pouring of flowable slag, that the latter comes into contact with the sections 1,2 and pipe 10. In addition, the cold slag fragments 15 form a zone which will become less hot than the poured remainder of slag in the bed 5, and which facilitates rapid flow-through of cooling water.

Detonation of the explosives causes the rupture of sections 2, and the formation of cavities in the slag 16 about the sections 2. From here, the water becomes distributed throughout the slag 16, together with steam resulting from contact of the water with the hot slag.

It will be appreciated that in this manner it is possible to supply relatively large quantities of cooling water to the slag 16, causing a cooling action which is substantially accellerated over what is attainable according to the prior-art approaches.

FIGS. 3 and 4 also show that the conduits composed of sections 1,2 can be further connected by connecting conduits 18, for which purpose connecting flanges 19, are provided. The conduits 18 are here connected with the lateral wall 9 by means of arms, brackets or the like. With this arrangement, where the conduits have longitudinally spaced apertures, the large area wetting of the slag from inside can be further facilitated. Thus, closure means may be provided in the sections 1 to prevent at the will of an operator the cooling water from flowing into the sections 2. It will them be forced to flow through the conduits l8 and escape through their apertures into the slag regions intermediate adjacent ones of the conduits which are composed of the sections 1 and 2. Conversely, water may also be allowed to pass both into the sections 2 and the conduits 18.

FIG. 4 shows in broken lines a cover plate which may overlie the sections 1, pipes 10 and conduits 18, extending outwardly from the wall 9, to protect them against the flowable slag and iron inclusions which are poured into the bed 5 from above.

FIG. 4a, finally, shows another concept of the invention. Here, the wall 9 is provided with a longitudinally extending slot 23 which has an open side facing towards the slag in the bed 5. The connecting conduit (or conduits) 18 is disposed in this slot 23 and its apertures may or may not face the open side. In this construction, where the conduit 18 is better protected against damage than by the plate 22, the water issuing from the conduit 18 flows out of the slot 23 and into the slag 16.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in the processing of iron-containing slag, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A method of processing slag, particularly ironcontaining slag, comprising the steps of providing a casting bed for the slag; arranging on said casting bed a plurality of tubular conduits having respective first and second sections; casting the flowable slag into said bed and forming therein a layer of hot slag which embeds said second sections of said tubular conduits; inserting explosive devices through said first sections into said second sections of said tubular conduits; detonating said explosive devices after said layer of hot slag has solidified so as to rupture said second sections and form cavities and cracks in the solidified layer of hot slag;

and introducing cooling water through said first sectrons into said second sections for entry into said layer of hot slag via said cavities and cracks.

2. A method as defined in claim 1, further comprising the step of anchoring said tubular conduits in said layer.

3. A method as defined in claim 1, wherein said eX- plosive devices comprise explosive caps.

4. A method as defined in claim 1, wherein said conduits extend at least substantially normal to the general plane of said layer, and further comprising the step of surrounding said outer sections with pieces of slag in solidified state. 

1. A method of processing slag, particularly iron-containing slag, comprising the steps of providing a casting bed for the slag; arranging on said casting bed a plurality of tubular conduits having respective first and second sections; casting the flowable slag into said bed and forming therein a layer of hot slag which embeds said second sections of said tubular conduits; inserting explosive devices through said first sections into said second sections of said tubular conduits; detonating said explosive devices after said layer of hot slag has solidified so as to rupture said second sections and form cavities and cracks in the solidified layer of hot slag; and introducing cooling water through said first sections into said second sections for entry into said layer of hot slag via said cavities and cracks.
 2. A method as defined in claim 1, further comprising the step of anchoring said tubular conduits in said layer.
 3. A method as defined in claim 1, wherein said explosive devices comprise explosive caps.
 4. A method as defined in claim 1, wherein said conduits extend at least substantially normal to the general plane of said layer, and further comprising the step of surrounding said outer sections with pieces of slag in solidified state. 